The sperm enzyme acrosin is thought to be involved in assisting sperm penetration through the glycoprotein envelope surrounding the egg. Acrosin has been isolated and characterized in terms of some of its physicochemical properties. Its enzymatic properties have been characterized using synthetic substrates (esterase and amidase activities). Its biological activity is presumably its proteolytic activity. However, the enzyme's activity as a protease has not been well characterized nor has the hydrolytic action of this enzyme on its biological or natural substrate been determined. Recently, egg envelopes have been isolated in sufficient quantities such that they can be chemically characterized. Therefore, the primary objective of the proposed research is to determine the mechanism of action of acrosin on its biological substrates, the glycoproteins composing the egg envelopes. Two animal systems will be used in parallel, the domestic pig Sous scrofa, and the frog, Xenopus laevis. Acrosin will be isolated from the sperm of both organisms. Acrosin's substrates, the zone pellucida in the case of the pig, and the vitelline envelope in the case of the frog, can be isolated in sufficient quantities to determine the susceptibility to proteolysis of the glycoproteins composing these cell structures, using radioisotopic and polyacrylamide gel electrophoretic techniques. Once the glycoprotein substrate(s) of acrosin has been determined, the enzymes purported role in assisting sperm to penetrate the egg envelope will be investigated using monoclonal antibodies directed against the acrosin substrates.